Patent GB-261734-A (GB)
Title: Improvements in or relating to railway safety devices
IPC: B61L3/00
Filed: 1926-11-10
Abstract: 261,734. Siemens & Halske Akt.-Ges. Nov. 21, 1925, [Convention date]. Track apparatus for stopping trains.-In order that, after having been stopped automatically or by the driver owing to a danger signal, a train may proceed only at or below a predetermined speed a normally energized relay 2 is provided which is de-energized in the stopping operation, and releases an armature 3 which can only be returned after lapse of an interval determined by the running down a clockwork mechanism (not shown), or after breaking lead seals with consent of a stationmaster &c. The armature 3 controls contacts which, in its released position, make the opening and closing of control circuits dependent upon a centrifugal speed device 12, 13 driven from a train axle. Three control circuits are described which, when energized, apply the brakes, cut off current from the train-driving motor, and release the. brakes, respectively, the last mentioned circuit being energized when the other two are de-energized, and vice versa. These circuits also include contacts 8, 9, 10 operated by the automatic train-stopping means, which contacts may be reset by the driver after an automatic stop in order to proceed or may be held against automatic operation in order to pass a danger signal, the speed limit above referred to being imposed in either case until the relay armature 3 has been returned to normal position. A track stop 30 is set under danger conditions to engage a lever 32.mounted, for example, on the roof of tho cab and move it anticlockwise thus opening a contact 4 in the circuit of relay 2. At the same time a detent 33 is released to allow a contact-drum 35 to be moved clockwise by a spring 37. Drum 35 carries bridging contacts 8.9, 10 co-operating with corresponding pairs of contacts 41-46, contacts 9, 43, 44 being normally closed, as shown. The drum may be returned or held against movement by a handle 100. A normally energized magnet 39 releases the brakes, which are applied by energization of a magnet 38. Current passes to the driving motor over contacts 142, 143 (bridged by a contact 141) and wire 144. Contact 141 is normally held closed against a spring 148 by a detent 145 but is released and opened by. the core 146 of a solenoid 147 when the solenoid is energized. Current is supplied from a lead 73 through, trolly 27 to a conductor 60 which, together with conductors 57, 58, 59 terminates in connectors 70, 71 for connection to corresponding conductors in adjacent coaches in which similar control devices may be provided if desired. The driver's switch comprises a movable contact strip 50 adapted in the normal position to bridge contacts 51, 53 and in the braking position to bridge eontacts 51, 52. Normally, current passes from conductor 60 over contacts 51, 53, contact strip 22 carried by the normally raised armature 3, drum contact 9 and conductor 59 to the brake release magnet 39. When the driver applies the brakes, current flows from conductor 60 over contacts 51, 52 and conductor 57 to the brake magmet 38. If a danger signal be overrun contact 4 is opened, breaking the circuit of relay 2 which also includes a contact strip 88 carried by armature 3. Armature 3 thus falls so that armature contact strips 21, 23 bridge corresponding pairs of contacts. A catch 103 retains armature 3 against resetting until released by clockwork mechanism, not shown, or after breaking seals, not shown. Drum contact 9 is opened, de-energizing magnet 39, and contacts 8, 10 are closed. Current then passes from conductor 60 over wires 78, 79, contact 8, wires 80, 58 to magnet 38, apply the brakes, and also passes over wire 78, contact 10, wire 82 and winding 147, whereupon the motor circuit is broken at contact 141. If the drum 35 be returned by handle 100 to the position shown, the brakereleasing magnet 39 is energized over contacts 91, 92 and arm 13 of the speed-controlled device, these contacts being in shunt with the now open contact 22 normally included in the brake release circuit. The train can thus proceed at a speed below a predetermined limit which, if exceeded, results in opening of contacts 91, 92 and deenergization of magnet 39. Pairs of contacts 93, 94 and 95, 96 are at the same time bridged by arm 13, so that current flows over wires 78, 101, contact 23, contacts 95, 96 and wire 19 to winding 147, again breaking the motor circuit, and current also flows over wire 78, 102, contacts 21, 93, 94 and wire 15 to magnet 38, applying the brakes. A similar speed restriction is imposed if the drum 35 be held against movement to allow the train to pass a danger signal without automatic brake application, as contact 4 is still opened by the stop 30.